The Different Methods of Soil Testing

Written by Angela

Reach out to Dreiym Engineering for any Corrosion, Electrical or Forensic Questions.

May 6, 2021

The Different Methods of Soil Testing

Though soil is most often associated with agriculture and plant growth, there are a lot of other industries that take the natural element into consideration. One industry that interacts with soil regularly is infrastructure.

For companies that want their facility’s components to last, they’ll perform a soil test before pursuing construction. This step is to assure that the material won’t compromise the quality of pipelines, tankers, or other features. The different methods of soil testing check for varying factors that determine soil quality. Acknowledging the soil makeup of your prospective construction space can save your business from hefty investments in future corrosion repair and replacement. Dreiym Engineering delves into the different approaches of soil analysis used today, as well as a brief breakdown of how those came to be.

A Brief History of Soil Sampling

Before we look at today’s different methods of soil testing, let’s reflect on the origin of the procedures.

The Beginning

Soil sampling has contributed to increased productivity and performance in several industries for centuries. In the late 1800s, agricultural farmers and scientists started inspecting soil a bit more meticulously, checking for facets that led to desired results. Assessing the plant nutrients in their soil samples informed agriculture operations greatly.

Through the 1900s

Come the early 1900s, land grant universities or institutions granted federal land and refined soil sampling techniques. An incredible amount of research that led into the 1940s advised farmers and scientists on best soil sampling practices.

Soil Science and Testing Today

Without the evolution in procedures over the last century, soil science would not have the intricate analysis and testing processes that it has today. Soil science keeps expanding, and industries utilize the ever-growing information stemming from the field as a tool for selecting the best soil for their needs. Soil testing is a mere subset of this type of science, as the procedures are still highly informed by the data gathered throughout the 1900s.

What Is Soil Corrosion?

We’re going to use a breakdown of soil corrosion to help us explain why soil testing is so important. Soil corrosion is a geologic occurrence that hinders metal and concrete that is buried directly in soil or bedrock. Excessive soil corrosion can lead to inconvenient pipeline failure, and in dire cases, ghastly eruption.

There are a variety of factors that lead to soil corrosion, making testing a necessary step to preventing expensive metals and concrete from corroding. Let’s take a look at which factors Dreiym Engineering soil analysis check for.

Factors To Check for With Different Soil Testing Methods

Soil testing companies will check your soil for the following factors:

  • Aeration
  • Electrical conductivity or resistivity
  • Moisture
  • pH
  • Dissolved salts
  • Sulfate content

The Different Methods of Soil Testing

So, how are those factors measured? Here are a few different approaches to testing out soil contents.

Testing for pH

Gathering soil’s pH will let you know whether it’s acidic, basic, or neutral. The pH scale is as follows:

  • Soil with a pH level below 7 is considered acidic. Highly acidic content is deemed by a pH balance of 0, such as battery acid.
  • A neutral pH balance will measure at a level of 7, containing neither basic nor acidic features.
  • Soil ranking a pH level of 8 or higher is considered basic. Highly basic materials may don a pH level of 14, such as lye.

Soil with high acidity is quick to corrode metals and concrete. The soil’s pH can be found using a slurry system that incorporates an electronic pH meter to determine the measurements.

Testing for Moisture Content

A few different methods used to measure soil’s moisture include the following:

  • Oven-drying method
  • Calcium carbide method
  • Torsion balance method
  • Pycnometer method
  • Sand bath method
  • Radiation method
  • Alcohol method

Of these options, oven-drying is a fairly popular method due to its accessibility. The process involves weighing a soil sample and drying it at 110 degrees Celsius, followed by another weight measurement. The difference clues professionals in on how much water was present in the soil.

Testing for Specific Gravity

Specific gravity is determined by comparing a substance’s density to that of water. These procedures help secure specific gravity measurement for soil:

  • Density bottle method
  • Pycnometer method
  • Gas jar method
  • Measuring flash method
  • Shrinkage limit method

Density bottle and Pycnometer approaches are the most common for soil testing this feature in soil. The Pycnometer method uses a gas pycnometer and a well-known density, often water, to acquire the soil’s density.

Testing for Dry Density

Dry density measurements refer to the weight of the soil particles within a soil sample. The void ratio and specific gravity of a sample must be determined prior to gathering its dry density. Dry density can be found through any one of these procedures:

  • Sand replacement
  • Water displacement
  • Core cutter

The water displacement method is the least common approach to determining dry density. Once measured, the sample’s dry density reading will then get categorized into one of three categories: dense, medium dense, loose.

Atterberg Limits Test

There are three different types of Atterberg limits tests, each measuring for different properties of fine-grain soil amid varying conditions. These tests are intended for measuring the critical water content of fine-grain soils:

  • Liquid Limit Test: Accurate soil analysis relies on a Casagrande’s liquid limit device to measure soil liquid limit.
  • Plastic Limit Test: Soil is mixed with water and shaped into a ball. The ball gets rolled around threads with 3 mm diameters. The process is repeated with a new sample and less water until the thread breaks, thus providing the soil’s plastic limit.
  • Shrinkage Limit Lest: This test informs the exact water content needed to fill the soil sample’s voids and is found using a complex mathematical formula.

How To Prevent Soil Corrosion

There are various methods to reduce soil corrosion, but cathodic protection routinely proves to provide the pipeline’s greatest line of defense from corrosion. It safeguards buried metals and concrete from a slew of corrosion, such as the following:

  • Messa attack corrosion
  • Putting corrosion
  • Pitting-type corrosion

Investing in cathodic protection helps keep your company safe, performing well, and up to government regulatory standards.

At Dreiym Engineering, we understand how vital durable, lasting infrastructure is to any business. That’s why we hone in on various analysis procedures that locate the source of your infrastructure troubles and offer preventative methods that stop them from amounting to irreversible damage. Our team of electrical consulting engineers is dedicated to providing comprehensive expertise to each of our clients, ensuring they acquire a sound understanding of the complex service they’re looking for. To learn more about our selection of engineering consulting, give Dreiym Engineering a call or send us an email today.

The Different Methods of Soil Testing

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